If can Convert multiple OST mailboxes to PST. You can easily convert single or batch OST files by using the eSoftTools OST to PST Converter program. You can simply convert OST to PST files while keeping the folder structure. This is a straightforward procedure that anybody, technical or non-technical, may follow to convert OST files to the Outlook data file format. This works with all versions of MS Outlook, including 2019.